1. Field of the Invention
This invention relates generally to metal detection devices and, more particularly, to devices designed to detect the inadvertent disposal of metal articles into waste receptacles. Specifically, the present invention relates to a metal detector designed to detect the inadvertent disposal of metal objects such as surgical instruments into disposal receptacles particularly useful in medical facilities and the like.
2. Description of the Prior Art
One of the major problems in the health care industry today is the high cost of patient care. While many factors contribute to this cost, one of these factors is the difficulty in controlling waste in a hospital environment. In the operating room, surgical instruments are inadvertently but routinely discarded along with the disposable drapes and gowns after an operation. These expensive instruments are intended for reuse, and their disposal represents a substantial waste. In addition, theft of such instruments and small metallic objects also occurs through such disposal mechanisms. A recent survey of randomly selected hospitals revealed that such wasteful disposal and theft of surgical instruments mounted to losses between $30,000-$50,000 per year per operating room. In a typical hospital having six to ten operating rooms, such loss is substantial.
Moreover, used disposable surgical drapes and gowns, by law, are required to be deposited in a so called "red bag" designated for infectious waste. Such red bags are approximately the size of a lawn and garden trash and leaf bag. The red bags are held for use in an open position in each operating room by a bag holder, typically in the form of a wheeled cart. Hospital personnel merely wad up used drapes and gowns and stuff them into the red bag for disposal. As can be readily appreciated, valuable surgical instruments, typically fashioned from an expensive grade of stainless steel, can easily become bundled with the used drapes and gowns, and disposed inadvertently or otherwise.
In penal institutions such as jails and prisons, prisoners are encouraged to participate in various jobs and vocational training programs including welding, mechanics and machining. Some inmates, consequently, have access to machine tools and metal stock materials from which they might fashion weapons. Receptacles for trash and laundry, although necessary in the daily operations of such penal institutions, create the potential for the smuggling by inmates of weapons and potential weapon stock material from shop and training areas to other locations. Accordingly, the monitoring and search of such receptacles place a substantial burden on guards, and thus increases the operating costs of these institutions.
Metal detectors of various types are well known in the art. U.S. Pat. No. 3,065,412 discloses a metal detector useful in its detection of metallic impurities in powders, while U.S. Pat. No. 4,821,023 discloses a walk-through metal detector useful at airports. Thus, metal detection devices have been applied in a wide variety of uses in the past. U.S. Pat. Nos. 4,632,253 and 4,782,970 disclose devices that are specifically designed to detect the inadvertent disposal of cutlery into a trash container in restaurant environments. Both these patent references disclose devices which are design to cover trash containers, the first one of which utilizes an inductive probe to detect metal cutlery so as to close a flap to prevent its disposal into the trash container, while the latter reference discloses a magnetic arrangement which traps cutlery prior to being deposited into the receptacle.
U.S. Pat. No. 5,001,425 discloses a device designed to cover a receptacle for use in a hospital environment to detect the inadvertent disposal of metal articles in such a receptacle. As is pointed out therein, however, a significant problem in a hospital environment, and in particular surgical environments, is the presence of numerous metal objects surrounding the receptacle. Such metal objects proximate the detector can cause the inadvertent triggering of the detector alarm system without a metallic article having actually been placed therein due to false readings from metal articles immediately surrounding or near the top of such a receptacle. Thus, there remains a need for a metal detector that is designed to detect the inadvertent disposal of small metal objects into a receptacle in a hospital, prison or kitchen environment, which is reliable and designed to prevent false signals from being registered due to the presence of metal articles on or near the top or exterior of such a receptacle without having been placed therein.